Algorithm to estimate notch root strain in tension using numerical analysis

作者：Kilambi Sreelatha^*; Tipton Steven M

来源：Theoretical and Applied Fracture Mechanics, 2015, 77: 1-13.

DOI：10.1016/j.tafmec.2015.01.002

• Notch root stress
• Notch root strain
• Elastic stress concentration factor
• Neuber's rule
• Glinka's strain energy density method
• Bulk plastic strain

Understanding the nonlinear stress and strain at the notch root is essential for estimating its fatigue life. Two popular analytical models currently in use are Neuber's rule and Glinka's strain energy density (SED) method. The success of Neuber's rule is shown to depend on material constitutive relation and the mode of loading, and the Glinka SED approach is shown to be limited to situations where the plastic zone size ahead of notch root is small, surrounded with predominantly elastic zone. This paper presents an empirical approach based on a normalized stress concentration factor as a function of maximum permanent strain for applications involving bulk plasticity. An algorithm is developed using finite element analysis of notched geometries with varying elastic stress concentration factor, Kt which is used to normalize the computed equivalent stress concentration factor. Results from the algorithm are demonstrated to estimate notch root strains to within 15% when maximum notch root strain is within 2-3%. An iterative algorithm is presented for applying this approach to other notch geometries to improve notch strain and fatigue life estimates.

• 出版日期2015-6